Lithium-ion batteries (LIBs) have attracted extensive attention in the past two decades for a wide range of applications in portable electronic devices such as cellular phones and laptop computers. Due to rapid market development of electric vehicles (EV) and grid energy storage, high-performance, low-cost LIBs are currently offering one of the most promising options for large-scale and high power energy storage devices.
In general, a lithium ion battery includes a separator, a cathode and an anode. Currently, electrodes are prepared by dispersing fine powders of an active battery electrode material, a conductive agent, and a binder material in an appropriate solvent. The dispersion can be coated onto a current collector such as a copper or aluminum metal foil, and then dried at elevated temperature to remove the solvent. Sheets of the cathode and anode are subsequently stacked or rolled with the separator separating the cathode and anode to form a battery.
Depending on the power of the internal combustion engine of the outdoor power equipment, the required peak current may be several hundred amperes up to approximately 1000 A. Lead-acid batteries are widely used for starting the internal combustion engines of vehicles, trucks, buses and the like. However, such lead-acid batteries have an undesirably high self-discharge rate. When the starting batteries are not being used for a long period of time, the batteries become depleted and are unable to start the engine. This problem can be even more serious when lead-acid batteries are stored at high temperatures since the rate of self-discharge increases as the temperature goes up.
There is another problem that frequently occurs with lead-acid batteries. The battery may not be able to deliver sufficient power at low temperature. Additional concerns occur if there is an emergency situation for which it is critical to start an engine, such as for starting an emergency vehicle, or starting a snow blower. Furthermore, lead-acid batteries have disadvantages of heavy weight and risk of electrolyte leaking from the battery. Therefore, alternative starting batteries are being sought.
U.S. Patent Application No. 20160233694 A1 describes a lithium-ion battery pack for use to start an internal combustion engine. The battery pack comprises an outer housing; a plurality of battery cells enclosed in the outer housing; and a charging circuit enclosed in the outer housing and coupled to the plurality of battery cells, wherein the plurality of battery cells can be an NMC (nickel magnesium cobalt) battery and/or a lithium iron phosphate battery. However, the battery pack does not include any features that allow the battery pack to satisfy the power needs in various temperature environments such as extremely cold environments.
CN Patent Application No. 105161768 A describes a vehicle starting battery containing a cathode made of lithium iron phosphate (LiFePO4). The starting battery includes at least four LiFePO4 battery cells connected in parallel or in series. However, this starting battery may not work well in cold weather conditions because of deterioration of discharge performance of LiFePO4 at low temperature, such as below about −10° C.
CN Patent Application No. 103427110 A describes a vehicle starting battery containing a cathode made of lithium vanadium phosphate. The starting battery can be used in cold environments, such as −40° C. However, there is no mention of the electrochemical performance of the starting battery except that under low temperature conditions. The lack of performance data limits us to gain a comprehensive understanding of such battery. In addition, the technology for large-scale production of lithium vanadium phosphate is not well proven, thereby offering considerable difficulty to commercial production. Furthermore, compared to cheaper materials like LiMn2O4 and LiFePO4, the cathode material lithium vanadium phosphate has a disadvantage of relatively high cost.
In view of the above, there is always a need to develop more reliable devices for instantly providing power for starting the engines of outdoor power equipment such as automobiles, boats, trucks and tractors.